Stapling devices have been widely used to bind a stack of punched paper sheets with a plastic resilient loop structure. The plastic resilient loop structure includes a plastic strip integrally formed thereon a plurality of curled loops in number corresponding to the holes in an edge margin of the punched paper sheets. A conventional stapling device is shown in FIG. 1(a), which is referred to U.S. Pat. No. 5,273,387. The stapling device principally comprises a punching mechanism 10, a finger structure 11, a fixture plate 12 and a knob 13. By means of the punching mechanism 10, a plurality of holes are created in an edge margin of a stack of paper sheets to be bound together. The principle and operation of the punching mechanism are well known in the art and need not be further described in detail herein. The finger structure 11, the fixture plate 12 and the knob 13 are cooperated for inserting resilient curled loops 141 formed on a plastic skeleton strip 14, as shown in FIG. 1(b), into the holes of the paper sheets so as to bind the paper sheets. In order to achieve this purpose, the plastic strip 14 is placed in a position behind the fixture plate 12. Then, the user manually shifts the plastic strip 14 to the right such that the cantilevered end of each finger penetrates the center of the corresponding curled loop 141. Then, the knob 13 is rotated to move the finger structure 11 outwardly from the fixture plate 12 until all the resilient curled loops 141 are propped open by the cantilevered ends of the finger structure 11. Then, the stack of paper sheets (not shown) are threaded by receiving the uncurled loops 141 via the pre-punched holes on the edge thereof. Subsequently, the knob 13 is rotated in the opposite direction to push the finger structure 11 back to its original position, and thus the resilient loops 141 are re-curled to bind the paper sheets.
The stapling device described above has some disadvantages. For example, it is difficult to manually move the plastic strip 14 because the plastic strip 14 is placed behind the fixture plate 13. In addition, the plastic strip 14 is readily slack and likely to become distorted once being exerted thereon an uneven force. After the paper sheets are completely threaded with the resilient loops 141, the plastic strip 14 is moved out from the stapling device to release the paper sheets by being manually shifted to and fro. This procedure for taking out the bound paper sheets is user-unfriendly.